Bill is correct. There were no "Roadster" seats before 1959. I apologize for such poor information and disseminating that information on SOC.
Approximately 1/2 of the later speedsters (late '57 and '58) were ordered/optioned/delivered with COUPE seats. That seems high to me, but that is what I got when I posed the question to the Registry. Dr. Thiriar is one expert and one source. His coffee table book is full of information. There are others equally and perhaps more qualified. Everyone has their favorite(s).
I do have "Roadster" Seats not "coupe" seats. Intermeccanica constructs the seat for their Roadster, Convertable D replica, not for a coupe. By the way, I have sat in these seats for 8-9 hour trips and, I guess because of my fat ass, was very comfortable for the entire trip.
Jim, or as you may call him Ward, has "speedster" seats in his car. Bill, (or is it George? I am a bit confused about this) you can tell by the shape of the seat. The "Roadster" or "Coupe" seats are flatter and wider, and the back (although this is not "shape") reclines. "Speedster" seats are similar to what is in your Beautiful, with outstanding fit and finish car that did not make the calendar. Your seats look nice. Perhaps your photo composition was "off".
Enjoy your car, Bill. That is really what it is all about, isn't it.